The transient equation has been solved for NbTi superconductor pool-cooled by Liquid Helium under the condition of heat input introduced as the disturbance, which is rectangular shaped both in space-wise and time-wise direction. The safety map, which shows the boundaries between quenching and recovery, has been plotted and the relation between those solutions and the static criterion, minimum propagating zone (MPZ), has been made clear. However, the relation to minimum recovery zone (MRZ) has not been clarified yet. Thus, in this research, the transient equation was solved for NbTi superconductor in the current region of MRZ and the safety map was made. The relation to minimum recovery zone (MRZ) was recognized in this solution.The pool boiling heat transfer from Nb tape-form superconductor to liquid helium was measured under the atmospheric pressure. The transient equation has been solved using this cooling characteristics of helium and the heat generation characteristics of Nb tape-form superconductor for the heat input introduced as the disturbance (above-mentioned). The results of quenching and recovery in the experiments for Nb tape-form superconductor were compared with these solutions and it was found that there was some discrepancy between them but the experimental results could be well simulated.